1. Field of the Invention
The invention relates to a device for displaying a parameter value, of the type having at least one row of light-emitting diodes each having a position input, and a control circuit with address outputs connected to the position inputs, whereby a signal sent from the control circuit through an address output connected to a specific light-emitting diode's position input causes illumination of that light-emitting diode.
2. Description of the Prior Art
Devices of the type described above are known for use in a number of different application fields for different kinds of indications. In general, such devices have one row of light-emitting diodes, also known as a bar graph, and a control circuit to turn on individual light-emitting diodes. For this purpose, the control circuit has address outputs connected to position inputs on the row of light-emitting diodes.
One problem is that an undetected fault could occur, for example, a short-circuit between two lines, since the display does not change very much. The nearest diode neighbor then 20 lights as well, which is not necessarily interpreted as a fault. In addition, an undetected erroneous indication could have consequences, such as for example termination of a process at the wrong point or operation of a process with an incorrect parameter value, such as temperature, etc.